Many types of goods and produce are shipped all over the world in conventional shipping containers. Often the goods being held in the container are fumigated prior to shipment by passing a fumigant gas of some type into the container to exterminate pests, parasites, insects or other vermin from another country, such as for example borers, lice, ticks, fleas or termites. Such containers also often contain timber dunnage and other bulk materials for packing around goods being shipped.
Although the containers can be substantially vented by known methods after fumigation, there are often residual amounts of fumigant which are adsorbed into the goods, produce and packing materials located in the container. These fumigants can slowly desorb over time during shipping of the re-sealed container. Also there can be free fumigant gas which becomes trapped in pockets between articles or packing materials in a container, particular when the container has been packed very full of cargo. Such gases can pose an environmental exposure risk for persons who may access the container upon its arrival and unpacking at its destination. Current methods of ventilation of an opened container, such as opening the container end doors for a period of time, are ineffective at fully eliminating trapped or desorbed gases, and highly dangerous from an occupational health standpoint, since the gases used for effective fumigation are extremely toxic.
In other situations, a container can be used to transport painted, enameled or lacquered items such as furniture or vehicles or other articles which can emit noxious smells or fumes over time which can become concentrated in the confined container space. Also if a chemical or a solvent being transported leaks during movement of the container this can create a residual gas in the container. If perishable goods are being transported and become moldy or rotten, this can also result in the generation of noxious gases. In any of these situations the gases or vapours generated in the container can pose an environmental exposure risk and possibly overpower or poison persons who may access and enter the container upon its arrival and unpacking at its destination.
In the specification which follows, when the term “residual gas” is used it refers to any measurable quantity of gases, fumes or vapours remaining in, or generated in, an enclosed chamber, the chamber having been sealed for a period of time. When the term “conventional shipping container” is used it refers to the commonly used containers of varying lengths and heights (for example 40-foot length or 20-foot length containers), well known in the cargo shipping and rail transportation industries. These containers normally are made of metal with corrugated side walls and an outwardly openable double door located at one end of the container for access thereinto.